Rotary cutter



F. P. MILLER ROTARY CUTTER Fi led June 10, 1929 Oct 18,' 1932.

IN VEN TOR. I flan/ C iZZeV I B y A T TOR NE Y.

Patented Oct. 18, 1932 PATENT orrica FRANK P. MILLER, 01? MEADVILLE, PENNSYLVANIA ROTARY CUTTER Application filed June 10,

This invention relates to rotary cutters and will be found to be disclosed in connection with a boring bar.

Briefly stated, an important object of t h1s invention is to provide a boring bar in which the adjustment of a single set screw or its equivalent is caused to bring about simultaneous and coextensive adjustment of the cutter blades to the end that such adjustment is facilitated and rendered more accurate.

Another feature of the invention will be found toreside in the means by which distortion of the bar or carrier for the blades may be compensated for to cause the several blades to have the same cutting dlameter as is the case when the bar or carrier is straigh and true.

Another aim of the invention is to provide a rotary cutter having simple and reliable means by which the several blades are urged into firm pressure contact-with the thrust receiving walls of the carrier, such as a bar, to avoid chattering. I

Other objects and advantages will be apparent during the course of the following description.

In the accompanying part of this application and in which like numerals are employed todesignate like parts throughout the same,

Figure 1 is a fragmentary vertical sectional view through a boring bar constructed in accordance with the invention,

Figure 2 is a vertical transverse sectional view taken on line 2-2 of Figure 1, I

Figure 3 is a fragmentary side elevation of the bar, the view being taken approximately at 90 to the illustration in Figure 1 Figure 4 is a vertical transverse sectional View taken on line 4-4: of Figure 3,

Figure 5 is a group perspective illustrating the blades and a locking pin therefor,

Figure 6 is a sectional perspective illust-rating an adjusting cam and an eccentric support therefor, D

Figure 7 is a fragmentary side elevation illustrating a slight modification of the invention.

In the drawing wherein for the purpose of illustration are shown several preferred drawing forming a Y 1929. Serial No. 369,881.

embodiments of the invention, the numeral 8 designates a boring bar of conventional formation, it being understood, however,that the inventive idea herein disclosed may be carried out in connection with rotary cutters 7 other than boring bars.

As shown in Figure 2, the bar Sis provided with the customary slot 9 extending diametrically therethrough and receiving a pair of cutter blades 10 arranged end to end and having the outer terminal portions thereof extended beyond the periphery of the-bar and ground with the usual cutting edges for engagement with the work. I

Figures 1 and 2 illustrate that the inner ends of the blades 10 arespaced sufficiently to allow an adjusting cam 12 tobe positioned between the same. Incidentally, the inner end portions of the, blades 10 are recessed for the reception of the hub portion of the cam. In carrying out the invention, the cam is provided on opposite sides thereof with lobes lhaving arcuate edges for engagement with the inner ends of the blades to move the same outward to increase the cutting'diameter of the tool.

One of the lobes is shown to be provided with an arcuate rounded extension or terminal portion engaged by a set screw 16 which when advanced, turns the cam 12 in a counterclockwise direction, as viewed in Figure 1, and thereby moves the cutters outward. The single set screw 16 is threaded into an appropriate socket in the bar and has the outer portion thereof formed with a groove or other tool mating means so that the screw may be either advanced or retracted.

The cam 12 is rotatably mounted on the eccentric intermediate portion 17 of a taper pin 18 adapted to be seated within a taper hole 20 disposed at right angles to the blade receiving slot 9 and intersecting the same. As shown in Figure 2, the taper pin 18 is designed tobe held in a firmly seated position within the transverse opening 20 by a set screw 22 threaded into one end portion of the opening 20 and engaged with the rear end of the pin. I

As suggested'previously, the intermediate or cam supporting portion 17 of the taper pin is disposed eccentrically with respect to the remaining portion of the pin so that by rotary adjustment of the pin, lateral distortion of the bar may be compensated for. In more specifically alluding to this feature of the invention, it is pointed out that such an arrangement causes one blade to extend a greater distance beyond the periphery of the bar than does the other blade; although the adjustment of the blades still will be simultaneous and coextensive.

To compensate for lateral distortion of the bar, it is a simple matter to loosen the binding or locking screw 22 and unseat the pin 18 from the reduced terminal thereof and then by the application of a screw driver to the grooved end of the taper pin, the same may be turned the extent necessary to cause the blades to have the same cutting diameter within the work. After the necessary adjustment of the taper pin, the locking or binding screw 22 is retightened to hold the taper pin in place and the subsequent advancement of the adjusting screw 16 will bring about the desired outward movement of the cutter.

After adjustment of the cutter, the same may be held firmly in place by a locking pin adapted to be seated in grooves 32 formed in extensions or ribs 34 in what might be said to be the forward edge portions of the cutters or blades. Referring now to Figures 3 and l, it will be seen that the locking pin 30 is held in place by a pair of set screws 36 threaded into the bar from opposite sides thereof and having tapered forward portions engaged with the oppositesides of the pin 30 and moving the same and the cutters laterally or backwardlyinto pressure contact with the rear thrust receiving wall of the slot 9. In this connection, attention is particularly invited .to the fact that the rounded rear edges of the blades 10 are adapted for contact with the similarly shaped rear or back edge of the slot 9 and that each blade has one edge thereof relieved as indicated at l0 so that the opposite edge of the blade may have a cam-like action against the opposed wall of the slot. Thus, when the blades are forced edgewise by the tightening of the set screws 36, the blades will be forced into firm pressure contact with the rounded back or rear wall of the slot 9 and such rounded wall will, in turn, have the effect of urging the blade-s flatly into engagement with the thrust receiving back wall of the slot. In this manner, chattering is avoided.

- It is illustrated in Fig. 1 that the cam 12 has a sort of compound action since it may not only be rotated a limited number of degrees tochange the cutting radius of the tool, but it may be moved bodily so that its position with respect to the bar is varied, this latter adjustability of the cam being important to compensate for limited misalignment or dis tortion of the bar.

Also it is important to observe that by engaging the adjusting screw 16 by one of the blade actuating lobes, such lobe is caused to serve a dual purpose. That is to say, the lobe functions first as a means of setting the associated blade and second, as a means for transmitting motion of the screw 16 to the cam. This arrangement avoids the necessity of employing a separate motion transmitting element or part between the set screw 16 and the cam with the result that it is unnecessary to cut away a portion of the bar for the accommodation of a separate motion transmitting part or element. As might otherwise be expressed, by engaging the set screw with a blade actuatin cam, a stouter bar is provided than would otherwise be the case.

Obviously, the purpose of truncating one of the lobes It is to cause the same to clear the adjacent locking pin 30.

In the form of invention illustrated in Fig ure 7, the boring bar is designated by the numeral and is provided with a transverse slot 52 extending entirely therethrough and receiving the blades 54. The adjusting mechanism illustrated in Figures 1 to 6 may be employed in the structure shown in Figure 7 and the application of lateral pressure to the pin 56 will move the blades 54 edgewise so that the transversely tilted back edge of the same will be engaged with the similarly tilted rear wall 58 of the slot 52 whereby the blades are forced into the desired pressure engagementwith the thrust receiving side wall of the slot to the end that chattering is avoided. 7

Having thus described the invention, what is claimed is:

1. In a rotary cutter, a carrier having a slot, blades in the slot, a rotatable cam wholly between the inner portions of the blades having oppositely arranged lobes engaged with the inner portions of said blades, a supporting pin for said cam and having an eccentric portion adjustable withrespect to said cam to elfect lateral bodily movement of the cam, and means independent of the said lateral bodily movement of the cam for turn ing said cam to vary the cutting diameter of the blades.

2. In a boring bar, a body having a slot extending entirely therethrough, blades in the slot, a cam having lobes engaged with the inner ends of said blades, a supporting pin for said cam and having a rotatably adjustable eccentric portion by which the position of the cam with respect to the blades may be varied, means holding the pin in an adjusted position, a blade adjusting device engaged directly with one of said lobes, and means securing the blades in an adjusted position.

3. In a boring bar, a body having a slot extending entirely therethrough, cutters arranged end to end within said slot and having the inner ends thereof spaced, a cam between the spaced ends of said cutters and formed with oppositely arranged lobes having arcuate edges engaging the inner ends of said blades, a pin intersect-ing said slot and provided with an eccentric intermediate portion supporting said cam, means to secure said pin in an adjusted position, an adjusting screw carried by said bar and engaged with one of said lobes to turn the cam, said cutters being provided with extensions having grooves, a locking pin in said grooves, and locking devices engaged with opposite sides of said pin and urging the pin into locking engagement with the blades.

4. In a rotary cutter, a carrier, blades supported by the carrier, a rotatable cam wholly between the inner portions of the blades and having lobes engaged with the blades, an adjusting device engaged with one of said blade engaging lobes, and a support for said cam having means by which the position of said cam and the lobes thereof may be shifted laterally with respect to said carrier to compensate for distortion of the bar.

5. In a rotary cutter, a body having a transverse slot, blades in said slot, a cam positioned between the ends of said blade and having lobes for pressure engagement with the inner ends of said blades, a pin carried by said body and having an eccentric portion supporting said cam, said pin being adjustable to allow the position of the cam and the lobes thereof to be varied with re spect to the body, and an adjusting device carried by said body and having motion transmitting engagement with one of said lobes.

4o 6. In a rotary cutter, a carrier, a supporting pin rotatably mounted in the carrier and having an eccentric portion, a cam adjustable rotatably on the eccentric portion, there being means whereby the pin may be angular- 1y adjusted to shift the eccentric, the cam and the blade laterally in the carrier.

7. In a rotary cutter, a carrier, a. supporting pin mounted in the carrier and having an eccentric portion, a cam rotatably adjustable on the eccentric portion, means whereb'v the pin may be adjusted angularly to shift the eccentric, the cam, and the blade laterally in the carrier, and an adjusting device for turning the cam on said eccentric independently ofthe said shifting of the cam with the eccentric.

In testimony whereof I aflix my signature.

FRANK P. MILLER. 

